Circuit interrupting apparatus



Apnl 18, 1933. J. D.'HILLIARD CIRCUIT INTERRUPTING APPARATUS Filed Nov. 27, 1929 Fig.2..

Inventor":

John D. Hilliorr'd,

(/cm His Attorney.

Patented Apr. 18, 1933 UNITED STATES PATENT OFFICE JOHN D. HILLIABD, OF GLENS FALLS, NEW YORK, ASSIGNOR '1'0 GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK CIRCUIT INTERRUZPTING APPARATUS Application filed November 27,1929. Serial No. 410,198.

My invention relates to circuit interrupting apparatus, and more particularly to means for interrupting an are drawn between relatively movable contacts during the circuit interrupting operation.

When contact members of a switch carrying comparatively large currents are opened to interrupt the circuit, the persistence of the resulting arc may be diminished in several ways. The are may be cooled and deionized by a suitable cooling medium or means; a fresh dielectric may be interposed in the path of the arc, thereby increasing the dielectric strength of the gap and preventing reestablishment of the arc;'the arc itself maybe mechanically lengthened until it finally breaks; or a combination of any of the above methods may be employed.

It is an object of my invention to provide an improved circuit interrupting apparatus wherein an are drawn between relatively movable contacts is mechanically lengthened and partially cooled or deionized, and more particularly wherein one or both of the extremities of the arc is or are forced transversely of a dionizin structure.

My invention will %e more fully set forth in the following description referring to the accompanying drawing, and the features of novelty which characterize my invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.

Referring to the drawing, Fig. 1 illustrates an elevationalview, partly in section, of circuit interrupting apparatus embodying my invention, Fig. 2 is an end view looking towards the left of the apparatus illustrated in Fig. 1, and Fig. 3 is a fragmentary'sectional view of a modification of the structure illustrated in Fi 1.

Referring to ig. 1, there is illustrated a switch casing or supporting structure 1 of insulating material having an opening or recess 2 within which relatively movable contacts of the switch are disposed. A stationary contact 3 is mounted with respect to the upper wall of the recess 2, and extends through the switch casing terminating in a binding post 4 to which is connected one terminal of a blow-out coil 5. The movable contact 6, pivotally mounted as at 7 within 'the switch casing, is normally biased by resilient means, as a spring 8, towards its open position. The movable contact is maintained in the closed position illustrated by a latch 9 which is adapted to engage a stud or lug 10 forming part of the contact 6. p

The latch 9 may be suitably controlled for tripping the switch either in response to abnormal circuit conditions, or at the will of the operator, and in the present instance there is provided automatic opening and closing means presently to be described.

It will be noted that the line 11, which is to be controlled, has in series therewith the blow-out coil 5, the switch contacts 36, and an electro-magnet 12 whose function it is to trip open the movable contact 6. The electro-magnet 12 comprises a movable core 13 guided for longitudinal movement within a bracket 14: secured to the switch casing and normally biased by a spring 15 in opposition to the pull of the magnet. That is, when normal current is traversing the electro-magnet 12 the tension of a spring 15 is sufficient to overcomethe magnetic forces tending to draw the core 13 within the coil, and to maintain the latch 9 in engagement with the lug 10. When an overload of predetermined magnitude, however, occurs on the line 11, the electro-magnet 12 is energizedsufiiciently to overcome the tension of spring 15, thereupon rotating the latch 9 in a counter-clockwise direction out of engagement with lug 10 so that the compression spring 8 is efiective to cause immediate clockwise or opening movement of the contact 6.

The reclosing mechanism comprises a toggle st"ucture 16 having a center pivot 17 to which is connected the movable core 13 of the electro-magnet 12. The toggle structure 16 is likewise connected to the movable core of an electro-magnet 18 which is resiliently biased, as by a spring 19, in an upward direction. When the switch is closed, the electro-magnet 12 serves to lock the toggle 16 in an overset position so that the tension of spring 19 is ineffective to cause buckling of the toggle. When, however, the electro-magnet 12 is sufliciently ener zed by an overload, the pivot 17 of the togg e is moved towards the left until it has passed dead center, after which the spring 19 acts to complete the collapse of the toggle. Operative y connected to the toggle 16 as at 20, is a lever 21 having a fixed pivot 22 and a lvotal connection 23 with the latch 9. It wi lbe noted, therefore, that during collapse of the toggle 16, the pivot will move upwardly causin clockwise movement of the lever- 21 so t at the latch 9 is moved longitudinally as well as transversely out of the path of lug 10.

With the structure in the open circuit po- 15 sition as described wherein the toggle 16 is collapsed, and the latch 9 at a position lower than that of the lug 10, the switch closing operation, in the event that the overload or a normal condition on the line does not still 0 obtain, ma be performed by energizing in any suitab e manner the electro-magnet 18 for causing straightening of the toggle. As the movable core of the electro-magnet' 18 is drawn downwardly against the tension of spring 19, the lever 21 is rotated in a counterclockwise direction carrying with it the latch 9. Assuming that the line conditions are now normal, the spring 15 returns the latch 9 to its vertical, or lug engaging position, so that as it moves upwardly it engages lug 10 to close the movable contact 6. Simultaneously therewith the sprin 15, when the toggle16 has been substantiay straightened, oversets, or locks the toggle so that the tripping mech- 85 anism is in the position originally described, and1 is ready for another switch operating c c e.

The apparatus above described for opening and closing the switch contacts may obviously assume different forms for the purpose of co-operating with the arcing structure resently to be described.

When the contacts 3 and 6 separate, an arc,

, depending in intensity on the quantity of power to be interru ted, may be drawn between the contacts. or the urpose of forcing the arc transversely oft e contacts, the usual pole pieces 24 coacting with the core 25 of the blow-out coil 5 extend along opposite sides of the contacts, and are provided with lateral extensions 26 forming opposing walls of an arc chute through which the are is to be blown. It will be apparent that the magnetic field between the pole positions and extensions thereof tends to cause the arc to travel rapidly outwardly away from the switch contacts, thereby causing the arc to be rapidly lengthened.

For the purpose of cooling and-deionizing the arc during this lengthening process there are provided discs or plates 27 of conducting material, as copper for example, formin upper and lower sections of the arcing c ute.

he plates 27 are held in position and suit- 05 ably spaced from each other by the insulating plates or walls 28 which are separated and spaced with respect to each other by spacing rods 29 and form a lining for the side walls of the arcing passage or chute. The copper plates 27 in the present instance are mounted at their opposite ends and lated by insulating material within slotsormed in the walls 28 so that they are spaced from each other by an air gap. Accordingly, as the arc moves outwardly through the arcing chute its op osite extremities are blown within the gaps etween the plates 27 and are divided into sections so that there is a voltage drop for eachsection of the are so divided. It is, of course, apparent that the spacin of the plates 27, and the number thereo may be readily designed so that the total voltage drop of the individual sections may be equal to or greater than the total voltage across the arc.

Since the heat generated by the arc is applied for a longer period near the contacts 3 and 6, provision may be made for more readily dissipating this heat by graduating the thickness and width of the plates 27 with respect to the heat of the are. In the present instance the plates 27 are made much thicker and wider at the contact end of the arcing chute so that the eater heat energy may be more readily dissipated by the greater mass and heat radiating surfaces of the plates. The mass and heat radiating surfaces of the plates are suitably graded so that the minimum mass and heat radiatin surface is at the outer or exhaust end of t e chute. Where the circuit interrupting device is to be operated at lower voltages, a single row of cooling plates 27 may be sufficient to deionize the arc, in which case a plate or skidlike structure of conducting material is used to form the opposite wall of the arcing chute instead ofthe other row of cooling plates. With this arrangement, one extremity of the arc moves along the conducting'skid while the other end is blown into the spaces between the cooling plates by a magnetic field as the arc noves rapidly towards the exhaust end of the chute. Due to the fact that the are adjacent the cooling plates 27 is very quickly broken up into a plurality of arcs in series with each other between the conducting plates, the cooling or deionizing action may take place very quickly to cause interruption of the arc. 7

Referring to Fig. 3, there is illustrated a modification of the structure above described wherein the arc is drawn by a bridging memher through the arcing passage or, chute comprising the deionizing or cooling structure. In this arrangement, the contacts 30 and 31 for carrying the main current coact with a bridging or conducting member 32 comprisin a pair of contact portions 33 at its extremlties. The bridging member 32 is carried by a rod 34 of insulating material suitably guided for longitudinal movement,

. as by the rollers 35. The cooling plates 36 tween the contacts 30 and 31, it jumps across chute away from the contacts. Accordingly,

to the contact portions 33 and partially. shunted across the bridging member 32 which is disposed within the arcing chute near the contacts. lhe resulting pressure of the gases developed by the arc tends to move and accelerate the bridging member 32 in a piston-like manner outwardly through the the extremities of the arc, as in the revious instance, are, blown into the spaces etween the cooling plates 36 so that the arc is divided into anumber of small arcs in series with each other, causing the arc to be cooled and deionized. With this arrangement the arc is lengthened and stretched out along its extremities until the summation of the individual voltage drops equals that of the voltage across the. contacts.

When the capacities to be interrupted by the switch are such that large amounts of gases are suddenly generated by the arc, the arrangement of the spaced cooling plates provides for proper Venting and mufllin'g of the generated gases.

It shall be understood that my invention is not limited to specific details of construetion and arrangement thereof herein illus trated, and that changes and modifications may occur to one skilled in the art without departing from the spirit of my invention.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. Ina circuit interrupting device, an arccooling structure comprislng a passage through which an arc may be forced, switch I contacts separable at one end of said passage,

and a plurality of spaced plates of conducting material forming one side of the passage whereby a portion of the arc is blown between said plates during movement thereof through the passage, said plates being graded in thickness and heat radiating surface so that the heat generated during the initial movement of the arc may be readily dissipated.

ing relativelly movable contacts, a magnetic blow-out coi having pole pieces arranged at opposite sides of t e contactswhereby the magnetic flux between the pole pieces tend to force the are formed between the contacts outwardly and away from the same, and opposing rows of plates of conductin material insulated and spaced from each 0t er forming an arc passage and disposed transversely of the path of the are so that the extremities of the are are blown into the spaces between the plates and cooled.

In witness whereof, I have hereunto set my hand this 25th day of November, 1929.

' JOHN ,D. HILLIARD.

2. In a circuit interrulpting device including a pair of contacts an a magnetic blowout device coacting therewith, an arc cooling structure comprising a plurality of plates of conducting material spaced and insulated from each other and disposed transversely of the direction of the magnetic blowout, said plates arranged in opposing rows to form a central passage throu h which the arc is blown upon opening 0 said contacts so that the extremities of said are are sub-divided by said plates.

3. A circuit interrupting device compris- 

